Hexagonal display array having close-packed cells

ABSTRACT

A display panel having a novel geometrical configuration. Each cell of the display array is equidistant from six cells adjacent to it. The geometrical configuration can be visualized as a hexagon, with a given cell comprising the center and the six adjacent cells comprising the apices of the hexagon. This improves the legibility of characters as compared to the standard rectangular matrix array. In particular, the average light intensity of diagonal and curvilinear lines is greatly improved. The hexagonal array offers substantial advantages for graphic displays and for displaying oriental languages, which are characterized by curved characters.

United States Patent Touw Jan. 7, 1.975

[54] IIEXAGONAL DISPLAY ARRAY HAVING 3,588,596 6/1971 Tech 313/108 R X O C CELLS 3,790,841 2/1974 Tsui et a1. 313/108 B [75] Inventor:

Corporation, Armonk, N.Y.

[22] Filed:

Sept. 26, 1973 Appl. No.: 400,746

Theodore R. Touw, Poughkeepsie,

Assignee: International Business Machines US. Cl 313/188, 313/201, 313/217 Int. Cl. H01] 11/00 Field of Search..... 40/28 C; 313/108 R, 108 A,

313/108 B, 108 C, 108 D, 108 E, 188 R, 201,

References Cited UNITED STATES PATENTS 2/1916 Brady 40/28 0 Loeb 340/336 X Primary ExaminerPaul L. Gensler Attorney, Agent, or FirmThomas F. Galvin [57] ABSTRACT 2 Claims, 10 Drawing Figures PATEHTEB JAN 71975 SHEEI 10F 3 PRIOR ART FIT PATENTEU 3.859.553

sum 30$ 5% overlap of the conductors.

BACKGROUND OF THE INVENTION The present invention relates generally to dot matrix displays. In my preferred'embodiment, the invention .j relates to the design of display panels which arecharacterized by'conduc tors arrayed in crossedrelationship, with each cell of thepanel being defined-by the area of DESCRIPTION OFTHEIIPRIOR ART I Designers of dot matrix displays have generally confined themselves to rectangular configurations. in particular, .the design of gaseous or plasma display panels has been limited to the standard matrix or orthogonal configuration in which conductive lands are arrayed in? parallel-columnsand rows, the lands in the columns being disposed orthogonally with respect to thelan'ds inthe rows." The gaseous displays have enjoyed commercial success in the display of alphanumeric and i graphi'c figures, particularly as display terminals for computers. For example,t he IBM 3,600 Finance Communication System .uses gas panels for information display; in addition, the University of Illinoishas developed a computer assisted instruction system that use a gas discharge display; terminal;

A problem inherent with the standard matrix display 1 configuration'is the relatively poor-legibility of diagonal and curvilinear strokes-,as compared to vertical and horizontal strokes which follow the geometrical pattern of the display cells...For'a square matrix, there is a greater distance between cellsalong the diagonal paths light intensity for diagonals and curves ,as' compared to I the intensity of the straight lines. The degradation of legibility of the former can be quite irksome. i i

The problem is'significantwhen informationcontaining a high proportion of diagonal and curvilinear BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are surface views, respectively, of a standard gas panel design and of my hexagonal design.

FIG. 3 illustrates a gas panel system including the novel display panel of my invention.

FIGS. 4a and 4b illustrate the character display achieved by a standard display and my hexagonal display using a 7 X 9 dot pattern.

FIG. 5 is an illustration of the characters achievable by my design in a 9 X 13 dot pattern.

FIGS. 6 and 7 illustrate Japanese and Chinese characters generated on my hexagonal design.

FIGS. 8 and 8a illustrate an embodiment of my invention in a gas panel which uses three drive lines rather than two.

7 DETAILED DESCRIPTION OF THE INVENTION square matrix comprised of gas chambers of a great number of isolated cells, the cells being defined by the crossing of orthogonal conductors l2 and 14. In the il- .lustra'ted embodiment of FIG. 1, the horizontal drive lines are shown as conductors disposed on the upper surface of the panel, while the vertical drive conductors are disposed on.the lower surface. The gas panel 10 includes anilluminable gas within a sealed envelope, and

those regions'within the vicinity of coordinate intersections of the vertical and horizontal drive lines are designated gas cells. For a more complete description of gas panel apparatus, reference is made to U.S. Pat. No.

3,611,019 in the name ofGeorge M. Krembs and asstrokes is displayed, e.g., in graphics. In additioniChinese and Japanese characters c'ontain'many curves and f I their display is generally not feasible on'the standard orthogonal display panel; this has been'a contributing.

factor to the lack of commercial success of these panels in displaying information in these languages.

SUMMARY OF THE INVENTION signed to the assignee of the present application. The

gas cells are selectively ignited or fired during a write operation by applying a first potential to associated horizontal drive line and a second potential to its associated vertical drive line of a magnitude such that the potential difference across the selected cell exceeds the ignition potential of the illuminab'le. gas.

Theforegoing' brief description of the typical gas panel is well known-to thoseof skill in the art and con- 'stitutes no part of my invention.- Attention is focused on the-geometrical design of the'panel in FIG. 1 which is I in the form of a standard matrix. For convenience, each cell is identified by its X: Y coordinates. Thus cell 4:4 hasfo'ur neighboringcells 'locatedalon g the X and Y fconductors, i.e., 4:3, 3:4, 4:5,and 5:4. Each of these cells is located equidistant from cell- 4:4 at a distance denoted in the drawing as a.

Y The other four neighboring cells 3:3, 3:5, 5:5 and 5:3

are-disposed diagonally with respect to the'orthogonal It is another object of my invention to greatly im prove the legibility of diagonal and curvilinear strokes on display panels.

These and other objects of the invention are accomplished by a novel geometrical configuration of the dis play cells wherein each cell is equidistant from the six cells adjacent to it. Geometrically, each cell is the center of a hexagon with the neighboring cells comprising the apices of the hexagon.

The foregoing and other objects, features and advan- A tages of the invention will be apparent from the following more particular description of the preferred emdrawings.

conductors from center. cell 4:4.--Thus the distance b betweencenter cell4i4 and one of the diagonal neighboring cells is larger than a. Geometrically, the distance b a 2 .:Vi ewedin this fashiomthe' disadvantage of the orthogonal display is immediately apparent. The

matrix design is perfect for symbols .which are c'haracterized' by horizontal and vertical lines,-such as symbol l, T and,E. However, II have found that for symbols which also contain diagonal components such as 7, 8,

W, etc.', the diagonal components are less legible than I metric design of a hexagonwherein a given cell is equidistant from 6 adjacent cells. Thusin FIG'I2, cell 7:7

is equidistant from cells 6:6, 67,628,713, 8:7, and 7:6.

The distance is denoted-by the letter in the drawing. With this configuration, a diagonal stroke has the same relative light intensity as a vertical or horizontal stroke. The only disadvantage is that the horizontal stroke in the array of FIG. 2 is not perfectly horizontal, but is rather in a staggered format. However, this is not a serious defect in any way because in the standard display, which may comprise from 2,500 to 20,000 cells per square inch,,the individual cells are not resolvable by the human eye. Thus, the distortion in the horizontal direction would not be noticed; however, the increase in legibility for diagonal and curved strokes is quite noticeable.

While the above discussion has compared my inventive hexagonal design with the standard rectangular design of a gaseous display panel, it will be obvious to those of skill in the display art that my invention is not limited to the preferred embodiment. It is applicable to any display technology which can support dot matrix symbol generation such as light emitting diode displays, electro-luminescent displays, fibreopitc displays, as well as gas discharge displays. In addition, it may have application to other dot matrix displays such as impact and heat sensitive printers.

Turning now to FIG. 3, my novel geometrical design is embodied in a gas panel display system. Display panel 30 has horizontal drive lines 28 and vertical drive lines 29 disposed on opposite sides of a gas filled enve lope 27.

In one commercial system, the upper drive lines disposed on the upper surface of panel 27 have apertures at the intersections with the lower drive lines 28 so that the gas ionization which occurs can be seen through the apertures. The glass insulator separating the electrodes from the gas also acts as the gas container. Other embodiments are possible. For example, one or both sets of conductors may be fabricated from a transparent conductor such as tin oxide. This is the embodiment shown in FIG. 3. Another, newer system using opaque metallic conductors is disclosed in a pending patent application, now abandoned Ser. No. 209,235 in the name of T. H. Haberland et al., filed Dec. 17, 1971 and assigned to the same assignee as the present application. In the embodiments illustrated in the Haberland et al. application, a unique conductor configuration is employed in which one of the conductor arrays comprises a set of two or more co-planar parallel conductor elements connected to a common drive line. The conductor elements in each set are spaced to permit radiant energy to pass therebetween when a site is selected. My invention is equally applicable to these three types of gaseous panel displays and to other variations which might occur to those of skill in the art.

Each cell in FIG. 3 is defined by the overlapping registry of a horizontal conductor 28 and a vertical conductor 29. Control signals are applied from horizontal selection circuit 31 and vertical selection circuit 33 to line drivers 32 and 34, respectively. The selection circuits are in the nature of decoders which address particular X and Y line drivers to select one or more cells for displaying a chosen character.

As can be seen with respect to either FIGS. 2 or 3, the formation of the hexagonal geometrical configuration in a gas panel entails offsetting every other cell in either the rows or columns. In the Figures the horizontal conductors are offset in alternate fashion to achieve the hexagonal configuration. Geometrically, the longest axis through the center of the hexagon, i.e.. the dimension between distal apices, is in the vertical direction. If the vertical. instead of the horizontal. conductors were offset, the longest axis of the hexagon would be in the horizontal direction. Although the pattern is different from the standard matrix display. the offset conductors are easily manufacturable with modern day printed circuit techniques.

Because the present invention is primarily directed to the conductor configuration rather than the gaseous display panel per se, the above description relative to operation is considered adequate for an understanding of the invention. For additional details regarding the operation of gaseous discharge panels and write. sustain and erase modes. reference is made to the aforementioned Krembs U.S. Pat. No. 3.601.019 and also to patents U.S. Pat. No 3,559,190 in the names of Bitzer et al. and U.S. Pat. No. 3,719,940 in the names of Lay et al.

Referring now to FIGS. 4a and 4b, a partial symbol set for a standard 7 X 9 pattern is shown compared to the same set achieved by my invention. The partial set illustrated in FIG. 4a is taken from an article by Allen G. Vartabedian entitled A Graphic Set For ASCII Using a 7 X 9 Dot Pattern." published in the magazine Information Display, November-December 1971. pp 1 1-16. The article illustrates the entire proposed graphic set of 96 characters of the USA Standard Code for Information Interchange (ASCII). The legibility of the Vartabedian font has been demonstrated to be about the best available today for square matrix displays.

Scrutiny of the characters in FIGS. 4a and 4b will demonstrate the superior legibility of my hexagonal design better than a verbal description. The chief difference is in the distance between each dot. which represents a cell in the display array. Because each of the cells in the hexagonal array is equidistant from the neighboring cells, the cells are "close-packed compared to the orthogonal array of FIG. 4a. In a physical array. this means a better average light intensity. This advantage is clearly illustrated in diagonals of numerals 7 and 11 and the letter W.

As previously mentioned, one apparent disadvantage of my configuration is in the offset nature of the horizontal lines, as illustrated in the letter T and the numeral 7 of FIG. 4b. The standard orthogonal design is more aesthetically pleasing; however the legibility of the horizontal lines is no different in practice because the density of the dots along the line are virtually identical.

FIG. 5 illustrates my invention in a 9 X 13 symbol size rather than 7 X 9 as in FIG. 4b. The 9 X 13 display is a high resolution display which has been found excellent for graphics such as are used in engineering and scientific design. It is in this type of format that my invention will have its greatest applicability, because the curves and diagonal lines commonplace in graphical representation are most legible using my hexagonal design. As illustrated in FIG. 5, the diagonals. as in the Figures, are closely packed and will be quite legible in a dot matrix optical display. Referring, for example. to the numeral 7, it is evident that the dots along the diagonal are as uniform as the dots along the horizontal. Similarly, the numeral 2 in FIG. 5 is substantially uniform throughout. This is a significant improvement over the same numerals achievable with the square dot matrix form-at.

FIGS. 6 and 7 are illustrations of Japanese and Chinese words, respectively, on a dot display matrix of my invention. One distinguishing characteristic of these oriental characters as compared to the English alphabet is the propensity toward graphic and curvilinear lines. The Chinese characters, in particular, are in fact word-pictures, where the characters are pictorial representations of the image to be conveyed. For various reasons, oriental languages are very difficult to convey on display systems. The most difficult obstacle to overcome is the word-picture of the language previously mentioned. The languages are made up of many hundreds of different basic symbols which can be combined to form words, as compared to the English language which can be conveyed adequately with fewer than 50 characters. Another problem is the legibility of the symbols on the standard orthogonal matrix. This latter problem is overcome by my invention in which diagonals and curves are as legible as vertical and horizontal lines.

Turning now to FIGS. 8 and 8a, there is shown an alternate embodiment of my invention in which three separate sets of conductive lines 40, 42 and 44 are used to define each cell, rather than the standard two intersecting lines as illustrated in the previous Figures. The three element set has been suggested for use in display arrays capable of performing more complicated functions than the commercially available displays. For example, it might be desirable to display more than one color from the cell. One way of doing this is to encapsulate two different gases which radiate at different optical frequencies between two separate containers. US. Pat. No. 3,588,596 in the name of Donald D. Tech describes such a panel, which would include three separate sets of conductors having different gases sandwiched between the conductors. The gases are chosen such that each gas gives off a different color when ionized. The embodiment shown by Tech in his patent is in the form of the orthogonal matrix. As illustrated in FIG. 8a, which is taken along line aa in FIG. 8 in my design, two gas chambers 51 and 54 are sandwiched between glass insulators 50, 52 and 53, 55 respectively.

6 The insulators separate the gases from conductors 40, 42 and 44.

The hexagonal configuration of the three-conductorset array is evident from the dashed lines emanating from cell 6:6 in the figure to the neighboring six cells. Cell 6:6 is the center of a hexagon with the six neighboring cells forming the apices of the hexagon. Viewed another way, any three cells in the matrix form an equilateral triangle, i.e., the angle formed between any two intersecting conductive lines is 60. Thus, at each intersection point comprising a cell, the Y-axis, Xl-axis and X2-axis lines are at angles of 60 with respect to each other.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and detail may be made therein without departing from the spirit and scope of the invention.

For example, the preferred embodiment of this invention is a gas display panel. However, my geometrical display design is not limited to gaseous display panels. It would be useful in any system wherein individual cells of uniform geometry are selectively addressed as a set to generate character displays.

I claim:

1. A gaseous discharge display panel comprising:

a gas filled envelope;

a first plurality of substantially parallel conductive lands disposed on one side of said envelope and a second plurality of substantially parallel conductive lands disposed on the opposite side thereof;

the coordinate intersections of said f rst and second lands being substantially orthogonal and defining a set of gaseous discharge cells;

said second set of lands having a staggered configuration such that each said cell is equidistant from six cells adjacent to said cell.

2. The gaseous discharge display panel of claim 1 wherein the cells comprise from 2,500 to 20,000 cells per square inch such that the individual cells are not resolvable by the human eye. 

1. A gaseous discharge display panel comprising: a gas filled envelope; a first plurality of substantially parallel conductive lands disposed on one side of said envelope and a second plurality of substantially parallel conductive lands disposed on the opposite side thereof; the coordinate intersections of said first and second lands being substantially orthogonal and defining a set of gaseous discharge cells; said second set of lands having a staggered configuration such that each said cell is equidistant from six cells adjacent to said cell.
 2. The gaseous discharge display panel of claim 1 wherein the cells comprise from 2,500 to 20,000 cells per square inch such that the individual cells are not resolvable by the human eye. 